Implantable medical devices for producing a therapeutic result in a patient are well known. Examples of such implantable medical devices include implantable drug infusion pumps, implantable neurostimulators, implantable cardioverters, implantable cardiac pacemakers, implantable defibrillators and cochlear implants. Some of these devices, if not all, and other devices either provide an electrical output or otherwise contain electrical circuitry to perform their intended function.
Such implantable medical devices, when implanted, are subjected to a harsh environment in contact with bodily fluids. Such bodily fluids can be corrosive to the implantable medical device. Typically, implantable medical devices are hermetically sealed, often in a titanium case, in order to protect the implantable medical device from the harmful effects of the bodily fluids with which the implantable medical device comes into contact.
Implantable medical devices often have components that may be assembled in separate, or at least separable, housings. An example is an implantable medical device containing a rechargeable power source, such as a chemical battery, which needs to be inductively charged transcutaneously from an external charging device. The external charging device typically has a primary charging coil which inductively stimulates a secondary coil associated with an implantable medical device. It may be desirable to locate the secondary coil away from, typically outside of, the housing containing the remaining components of the implantable medical device primarily in order to segregate the heat generating component of the secondary coil from the remainder of the implantable medical device. Thus, the secondary coil is sometimes contained in a separate assembly than the rechargeable power source and/or therapeutic componentry of the implantable medical device. It is still necessary to electrically connect the secondary coil to at least some of the remaining components. Further, it may be desirable to physically secure the internal antenna housing the secondary coil with the housing of the remainder of the implantable medical device.
It is difficult, however, to achieve a secure and reliable mechanical and electrical connection which is secure from the deleterious effects of body fluids into which the implantable medical device will come into contact following implantation.